Answer:
Without a table, we can't really complete one.
This can be easier though if you realise that:
y = x^2 - x
is identical to:
y = x(x - 1)
In other words, the table values are just 1 × 0, 2 × 1, 3 × 2, 4 × 3, etc., giving you the series (starting with x = 1)
0, 2, 6, 12, 20, 30, 42, 56, 72, 90, 110, 132, ...
This If you plot this on a graph, it gives you a parabola that opens upward. It's vertex is at (0.5, -0.25)